Electromagnetically actuated valve

ABSTRACT

The present invention relates to an electromagnetically actuatable valve having a longitudinal valve axis ( 3 ), having an electromagnetic circuit ( 1, 2 ), having a movable actuating member ( 25 ), that cooperates with a fixed valve seat ( 23 ) for opening and closing the valve, and having an outlet opening ( 8 ) that is configured downstream of the valve seat ( 23 ). The actuating member ( 25 ) is executed in a bowl, trough, or saucer shape, having an actuating leg ( 26 ) and a supporting leg ( 27 ) that is configured so as to be substantially perpendicular to the former. The actuating leg ( 26 ), as a movable part of the actuating member ( 25 ), cooperates with an upper layer ( 15 ) of atomization disk ( 12 ), so as to form a sealing valve.  
     The valve is especially well-suited for use as a fuel injector in an internal combustion engine, especially in a mixture-compressing, spark-ignition internal combustion engine.

BACKGROUND INFORMATION

[0001] The present invention is based on an electromagnetically actuatable valve according to the species of the main claim.

[0002] From German Patent 39 43 005, an electromagnetically actuatable fuel injector is already known, in which a plurality of disk-shaped elements is arranged in the seat area. When the magnetic circuit is excited, a planar valve plate, acting as a planar armature, is lifted off from a valve seat plate that is situated opposite and cooperates with the valve plate, the two together constituting a plate valve part. Arranged upstream of the valve seat plate is a swirl element, which induces in the fuel flowing to the valve seat a circular rotational motion. A stop plate limits the axial path of the valve plate on the side opposite the valve seat plate. The valve plate is enclosed by the swirl element so as to permit a large amount of play; in this way, the swirl element provides a certain guiding function for the valve plate. Introduced on the lower front side of the swirl element is a plurality of grooves running tangentially, which extend from the outer periphery to a central swirl chamber. As a result of the contact of the swirl element at its lower end face on the valve seat plate, the grooves function as swirl channels.

[0003] In the German Laid-Open Print 196 07 288, the so-called multilayer electroplating process was described in detail for manufacturing perforated disks that are especially well-suited for use in fuel injectors. This manufacturing principle of producing disks through the single or multiple electroplating metal deposition of various patterns on one another so that a unitary disk is produced, is expressly included in the disclosure content of the present invention.

[0004] From German Laid-Open Print 195 23 915, a micro-valve is known that is manufactured using multilayer electroplating. A valve lower part, which includes at least one armature and one movable valve-closure member, is built up in a plurality of layers through electroplating metal deposition.

ADVANTAGES OF THE INVENTION

[0005] The electromagnetically actuatable valve according to the present invention having the characterizing features of the main claim has the advantage that it can be manufactured in an especially simple manner and so as to be extremely miniaturized. The valve according to the present invention, in the sealing seat area ideally does not have any large storage volumes, which could make for a large dead volume. Rather, the valve seat is directly integrated on an atomization disk, so that no additional volume at all arises between the valve seat and the intake into the atomization disk. In this way, the quantity of fluid stored in this area is kept extremely small. In a valve that is used as a fuel injector, it is therefore possible as a result to effectively avoid uncontrolled secondary spattering in engine operation.

[0006] As a result of the measures indicated in the subclaims, advantageous refinements and improvements of the valve indicated in the main claim are possible.

[0007] It is advantageous to configure the actuating member as having two legs, a supporting leg and an actuating leg, the supporting leg running parallel to the longitudinal valve axis, and the actuating leg running substantially perpendicular to the longitudinal valve axis. The actuating member can advantageously be manufactured as having very small dimensions and, due to the material used, e.g., spring steel sheet, so as to have a very small mass. Due to the small movable mass of the actuating leg as the single movable part, very short switching times of the valve can be achieved, and it is possible to maintain an extremely low wear on the sealing seat.

[0008] The individual parts of the valve can be assembled very simply. Thus the supporting leg has a wedge-shaped chamfer, for example, on its lower end, for securing the actuating member through a wedging-in process.

DRAWING

[0009] One exemplary embodiment of the present invention is depicted in the drawing in simplified form and is discussed in greater detail in the description below. FIG. 1 depicts a partially represented, electromagnetically actuatable valve in a miniaturized type of construction.

DESCRIPTION OF THE EXEMPLARY EMBODIMENT

[0010] The electromagnetically actuatable valve depicted as an exemplary embodiment in FIG. 1, by way of example in the form of an injector, is especially well-suited for use in fuel injectors of mixture-compressing, spark-ignition internal combustion engines. On the other hand, the valve according to the present invention can also be used for the controlled dispensing of the most varying fluids, e.g., as an inhaler, as the nozzle of an ink-jet printer, or as an atomization nozzle in the chemical or pharmaceutical industries.

[0011] The valve has a magnetic circuit, which acts as the actuator of the valve. The magnetic circuit includes, on the one hand, a solenoid coil 1 and, on the other hand, a magnetic holder 2 that surrounds solenoid coil 1 at least partially. Annular magnetic holder 2 surrounds solenoid coil 1, e.g., on three sides and acts as the internal pole of the magnetic circuit. On the basis of its reversed U-shaped profile, magnetic holder 2 provides for an especially compact and short design of the valve in the area of solenoid coil 1.

[0012] The very compact magnetic circuit is mounted in a valve housing 4 that is configured so as to be concentric with regard to a longitudinal valve axis 3. In valve housing 4, a traversing longitudinal opening 5 is provided, which extends along a longitudinal valve axis 3. Valve housing 4 on the basis of its longitudinal opening 5 also functions as a fuel intake pipe, longitudinal opening 5 representing a fuel supply channel. Provided in longitudinal opening 5, on the intake side, is, e.g., an undepicted fuel filter, which acts to filter out such fuel components that, due to their size, could cause blockages or damage in the injector.

[0013] Valve housing 4 has, for example, a tubular housing casing 6, in which longitudinal opening 5 extends so as to have a substantially constant diameter, and a housing base 7, which forms the downstream termination of valve housing 4 and therefore of the entire valve. In housing base 7, an outlet opening 8 is provided, which ultimately represents an extension of longitudinal opening 5, but which has a smaller opening width. The configuration of housing base 7 determines the assembly direction of the interior valve components, which can therefore be inserted only from the supply side in accordance with the so-called ballpoint-pen installation principle.

[0014] Placed on interior base 11 of housing base 7 is first, e.g., a multilayer atomization disk 12. This atomization disk 12 is built up, for example, in a so-called multilayer electroplating process, a multilayer electroplating metal deposition, and it is inserted into the valve as a compact individual component part.

[0015] In FIG. 1, a three-layer, i.e., three-level, atomization disk 12 is depicted in its function as a swirl disk. In the valve according to the present invention, however, other quite different designs of atomization disks can be used. The layers of atomization disk 12 are deposited one after the other using electroplating, so that each succeeding layer, through electroplating adhesion, bonds firmly to the layer below. Atomization disk 12 has an exterior diameter such that it can be fit to longitudinal opening 5 leaving a certain distance. The layers of atomization disk 12 are designated below in accordance with their function as cover layer 15, swirl-generating layer 16, and base layer 17. As can be seen from FIG. 1, upper cover layer 15 is designed so as to have a smaller exterior diameter than both next layers 16, 17. In this way, it is assured that the fuel, when the valve is opened, can flow on the outside past cover layer 15 and therefore can enter unobstructed into exterior intake areas 18 of, for example, four swirl channels 19 emanating from the exterior periphery of atomization disk 12 in the central swirl-generating layer 16.

[0016] Upper cover layer 15 represents a closed metallic layer, which does not have any opening areas for through-flow and therefore also functions as valve seat 23. In swirl-generating layer 16, on the other hand, a complex opening contour is provided, which extends over the entire axial thickness of this layer 16. The opening contour of central layer 16 is formed by an interior swirl chamber 20 and by a multiplicity of swirl channels 19 that discharge into swirl chamber 20. The, for example, two to eight swirl channels 19 discharge tangentially into swirl chamber 20. While swirl chamber 20 is completely covered by cover layer 15, swirl channels 19 are only partially covered, because the exterior ends that are facing away from swirl chamber 20 form intake areas 18 that are open towards the top. As a result of the tangential discharging of swirl channels 19 into swirl chamber 20, the fuel takes on a rotational impulse, which it maintains both in a central circular outlet opening 22 in lower base layer 17, as well as in outlet opening 8 of valve housing 4.

[0017] Atomization disk 12 is built up in a plurality of metallic layers using electroplating deposition. As a result of the deep-lithographic, electroplating manufacturing process, there are specific features in the contouring, of which several are listed here in summary form:

[0018] layers having a thickness that is constant over the disk surface,

[0019] substantially perpendicular notches in the layers made by the deep-lithographic patterning, the layers each forming hollow spaces that permit through-flow (deviations of approximately 3° with regard to the optimally perpendicular walls can occur for production-engineering reasons),

[0020] desired undercuts and overlaps of the notches as a result of the multilayer design of individually patterned metal layers,

[0021] notches having any cross-sectional shapes that have essentially axis-parallel walls,

[0022] a one-piece design of the atomization disk, because the individual metal depositions are carried out directly one on top of the other.

[0023] At its upper limiting edge, atomization disk 12 forms a valve seat 23 at cover layer 15. As a valve member that opens and closes the valve, an actuating member 25 is provided that is bowl-, trough-, or saucer-shaped. Actuating member 25, functioning both as armature as well as valve-closure member, cooperates with valve seat 23 as a sealing valve. Actuating member 25, which has an L-shaped cross-section, has two legs, one, an actuating leg 26, being oriented so as to be substantially perpendicular to longitudinal valve axis 3, and the other, an annular supporting leg 27, being oriented parallel to longitudinal valve axis 3, the legs therefore running so as to constitute a substantially perpendicular bend with regard to each other.

[0024] After the assembly of atomization disk 12, actuating member 25 is inserted into longitudinal opening 5. Supporting leg 27 at its lower end has a wedge-shaped chamfer 28, which is pressed between the inner wall of valve housing 4 and atomization disk 12, so that it is wedged in at central swirl-producing layer 16. Because this takes place over the entire periphery of atomization disk 12, atomization disk 12 is fixed at the valve end in a secure, reliable, and centered manner.

[0025] Actuating leg 26 is also executed in an annular shape, because it has an interior cutout 29. Edge area 30 of cutout 29 runs in the flow direction so as to expand in a truncated-cone shape, and it forms the actual valve-closure element, which corresponds with valve seat 23 on cover layer 15. When the valve is closed, actuating leg 26 of actuating member 25 contacts valve seat 23. The pressure force with which actuating member 25 presses onto valve seat 23 results from the spring stiffness of the material that is used in actuating member 25 (e.g., spring steel sheet) and from the resting pressure of the fuel exerted thereon.

[0026] Solenoid coil 1 is preassembled in magnetic holder 2, and subsequently this magnetic circuit assembly is also inserted into longitudinal opening 5. A radial excess in the exterior diameter of magnetic holder 2 provides for the desired axial fixing as a result of the radial pressure in valve housing 4.

[0027] To release the through-flow in the area of valve seat 23, actuating member 25, at edge area 30 of actuating leg 26, must lift off from atomization disk 12 by a defined stroke. In this context, the actuation of the valve takes place in a familiar manner, electromagnetically. The opening stroke is set by the plastic deformation of magnetic holder 2 in its already assembled state. For this purpose, it is possible to exert pressure axially on magnetic holder 2 using, for example, a deformation tool 35 that is only sketched in. The spring force of actuating member 25 is set in advance in the axial direction also through plastic deformation.

[0028] The stroke of actuating member 25 is therefore determined, inter alia, by the installation positions of actuating member 25 and magnetic holder 2. The one end position of actuating member 25, when solenoid coil 1 is not excited, is determined by the position of actuating leg 26 on valve seat 23, whereas the other end position of actuating member 25, when solenoid coil 1 is excited, results from the position of actuating leg 26 on interior downstream end face 37 of magnetic holder 2, which serves as the interior pole.

[0029] The compact design of the individual components of the valve makes it possible to manufacture a miniaturized valve having an external diameter of only roughly 4 mm. 

What is claimed is:
 1. An electromagnetically actuatable valve having a longitudinal valve axis (3), having an electromagnetic circuit (1, 2), having a movable actuating member (25) which cooperates with a fixed valve seat (23) to open and close the valve, and having an outlet opening (8) that is configured downstream of the valve seat (23), wherein the actuating member (25) is executed so as to have a bowl, trough, or saucer shape, and so as to have an actuating leg (26) and a supporting leg (27) that is configured so as to be substantially perpendicular to the former.
 2. The valve as recited in claim 1, wherein the supporting leg (27) runs parallel to the longitudinal valve axis (3), and the actuating leg (26) runs substantially perpendicular to the longitudinal valve axis (3).
 3. The valve as recited in claim 1 or 2, wherein only the actuating leg (26) forms the movable part of the actuating member (25).
 4. The valve as recited in one of the preceding claims, wherein the supporting leg (27) runs in annular fashion, and the actuating leg (26) is also configured in annular fashion as a result of an interior cutout (29).
 5. The valve as recited in claim 4, wherein the actuating leg (26), at the edge area (30) of the cutout (29), forms a valve-closure member.
 6. The valve as recited in claim 5, wherein the edge area (30) of the cutout (29) runs in the flow direction so as to expand in a truncated-cone shape.
 7. The valve as recited in one of the preceding claims, wherein the supporting leg (27) at its lower end has a wedge-shaped chamfer (28) for securing the actuating member (25).
 8. The valve as recited in one of the preceding claims, wherein, upstream of the outlet opening (8), a multilayer atomization disk (12) is arranged in the valve.
 9. The valve as recited in claim 8, wherein an upper layer (15) of the atomization disk (12) has a valve seat (23), with which the actuating leg (26) cooperates, to open and close the valve.
 10. The valve as recited in claim 8 or 9, wherein the supporting leg (27) is wedged between a valve housing (4) and a further layer (16) of the atomization disk (12) that is located downstream of the upper layer (15).
 11. The valve as recited in one of claims 8 through 10, wherein the atomization disk (12) is configured as a swirl disk having at least one swirl channel (19).
 12. The valve as recited in one of claims 8 through 11, wherein the atomization disk (12) can be built up in a plurality of layers through electroplating metal deposition.
 13. The valve as recited in one of the preceding claims, wherein the electromagnetic circuit is formed by a solenoid coil (1) and a magnetic holder (2), the magnetic holder (2) being executed so as to have an annular shape and a U profile, and the solenoid coil (1) being arranged within the U profile.
 14. The valve as recited in claim 13, wherein the opening stroke of the actuating member (25) can be set through the plastic deformation of the magnetic holder (2).
 15. Use of the valve as recited in one of claims 1 through 14 as a fuel injector in an internal combustion engine, especially in a mixture-compressing, spark-ignition internal combustion engine. 